HYMENOPTERA OF THE HAWAIIAN ISLANDS. 233 



(it is remarkable in how many of the Hymenoptera taken 

 near the crater o£ the active volcano this colour appears) . 

 The eyes are separated in the last two species named above, 

 and are excessively finely facetted. The face is little con- 

 cave. The denticulation of the sixth joint of the antennae 

 is only moderate. The ventral segments resemble those 

 of C. stygius and C. adspectans. 



In the same locality as the male C. rubro-caudatus I 

 procured two examples, which are probably its female. 

 As, however, they differ rather exceptionally, I hesitate 

 to assign them to this species with certainty, for the wings 

 are entirely devoid of the blue tint. In other respects 

 they might well be the female C. rubro-caudatus. The 

 penultimate and apical segments in the hind body of these 

 specimens do not seem to differ much from the same parts 

 in the female C adspectans. 



Occurred on Maun a Loa, Hawaii, at an elevation of 

 about 4000 feet, in close proximity to the burning crater. 



Larrid^. 



46. Pison iridipennis. 



Pison iridipennis. Smith, Proc. Linn. Soc. xiy. p. 676. 



Hab. Honolulu. 



47. Pison hospes. 



Pison hospes, Smith, lih. cit. p. 676. 



Hab. Oahu, Kauai, and Maui. Not uncommon. 



Sphegid^. 

 48. PelopcBus dement arius. 



Sphex ccementaria, Drury, Exot. Ins. i. p. 105. 



Pelopeus flavipes, Fab. Syst. Piez. p. 202 ; Smith, Proc. Linn. Soc. xiv, 

 p. 676. 



A common species in the islands, and, according to 



